Flexible printed circuit board (FPCB) are generally known to contain a flexible copper-clad laminate (“FCCL”), which is produced by forming a resin layer as an insulating resin layer on a copper foil. In the flexible copper-clad laminate having thin copper foil, polyimide has been used as a resin, pressed under pressure to the thin copper foil. A laminate of thin copper foil and a polyimide layer can be manufactured by a roll-to-roll process such that polyimide is placed on a thin copper foil with a carrier layer, in which the carrier layer is facing to the hot pressing roller. When the thin copper foil laminated to polyimide and consolidated at elevated conditions of temperature and pressure, the high temperature (350° C.) will cause the carrier layer of flexible copper-clad laminate to partially stick to the hot pressing roller. During hot pressing, if part of the carrier layer is stuck to the hot pressing roller, as hot pressing is a continuous process, a flexible copper clad laminate will be fed and wound continuously, thereby creating a pulling force between the hot pressing roller and the carrier layer. Therefore, the bonding strength of the carrier layer and thin copper foil by rolling becomes poor and non-uniform, and then wrinkles and blisters can happen on the interface between the carrier layer and the thin copper foil. Sometimes it causes the carrier layer to partial peel off from the thin copper foil before using the composite to manufacture flexible printed circuit board. These and other drawbacks, inefficiencies, high cost of raw materials, inability and/or difficulty to produce greater number of circuits per unit volume and reduction in defective PCBs produced are avoided by following the various embodiments set forth below.